I’m sure that if you have taken an interest in anabolic steroids you have noticed the similarities on the labeling of many drugs. Let’s look at testosterone for example. One can find compounds like testosterone cypionate, enanthate, propionate, heptylate; caproate, phenylpropionate, isocaproate, decanoate, acetate, the list goes on and on. In all such cases the parent hormone is testosterone, which had been modified by adding an ester (enanthate, propionate etc.) to its structure. The following question arises: What is the difference between the various esterified versions of
testosterone in regards to their use in bodybuilding?
Esterification of an injectable anabolic/androgenic steroid basically accomplishes one thing, it slows the release of the parent steroid from the site of injection. This happens because the ester will notably lower the water solubility of the steroid, and increase its lipid (fat) solubility. This will cause the drug to form a deposit in the muscle tissue, from which it will slowly enter into circulation as it is picked up in small quantities by the blood. Generally, the longer the ester chain, the lower the water solubility of the compound, and the longer it will take to for the full dosage to reach
general circulation.
Slowing the release of the parent steroid is a great benefit in steroid medicine, as free testosterone (or other steroid hormones) previously would remain active in the body for a very short period of time (typically hours). This would necessitate an unpleasant daily injection schedule if one wished to maintain a continuous elevation of testosterone (the goal of testosterone replacement therapy). By adding an ester, the patient can visit the doctor as infrequently as once per month for his injection, instead of having to constantly re-administer the drug to achieve a therapeutic effect. Clearly without the use of an ester, therapy with an injectable anabolic/androgen would be much more difficult.
